WikiLeaks, the whistleblower website, has not yet responded to the demand made by the US last week to return all classified leaked documents on Afghan war, Pentagon and State Department officials have said.

"We are still waiting for WikiLeaks to respond to our demands made last week. We have not been contacted by them. We have not got any indication that they intend to comply," Pentagon deputy spokesman Col Dave Lapan told reporters.

About a week ago, Pentagon had asked WikiLeaks to return to it all the classified documents that it has gained access to through various sources.

"The Defence Department demands that WikiLeaks return immediately to the US government all versions of documents obtained directly or indirectly from the Department of Defence databases or records," Pentagon spokesman Geoff Morrell said.

"Looking at track record of WikiLeaks, they are as unpredictable as North Korea. We have seen before, they have said that they are going to release things, but wasn't released," Lapan said.

"We are obviously concerned with any additional document that they would release," he said in response to a question.

Both the Pentagon and State Department spokesmen denied that they were aware of any US effort asking other countries to launch their own investigation against WikiLeaks.

"We have touched a lot of bases over the last 24 hours and I'm not aware that anyone at the Department of State has had that kind of conversation with a foreign government," State Department spokesman P J Crowley said.

"I think, the Attorney General has indicated, we are evaluating ? well, step back further ? we are obviously investigating directly the leak itself. That investigation is led by the Department of Defence. We are supporting that investigation," he said.

"But the Attorney General has indicated that we will aggressively pursue any case where we believe our laws have been broken. I would think that any other country that has been similarly affected by this action would consider similar steps, but those are decisions for individual countries to make," Crowley said.

No country had been approached to encourage such a step and the conversations were on the joint concerns over the issue, he said.

"But I'm not aware that we've had any conversation where we have said, 'Hey, you should look at prosecuting person X, Y, or Z'," the official added.